The ungleich kubernetes infrastructure » History » Revision 42
Revision 41 (Nico Schottelius, 10/06/2021 08:02 AM) → Revision 42/219 (Nico Schottelius, 10/06/2021 08:07 AM)
h1. The ungleich kubernetes infrastructure and ungleich kubernetes manual
{{toc}}
h2. Status
This document is **pre-production**.
This document is to become the ungleich kubernetes infrastructure overview as well as the ungleich kubernetes manual.
h2. k8s clusters
| Cluster | Purpose/Setup | Maintainer | Master(s) | last verified |
| c0.k8s.ooo | Dev | - | UNUSED | 2021-10-05 |
| c1.k8s.ooo | Dev p6 VM | Nico | 2a0a-e5c0-2-11-0-62ff-fe0b-1a3d.k8s-1.place6.ungleich.ch | 2021-10-05 |
| c2.k8s.ooo | Dev p7 HW | Nico | server47 server53 server54 | 2021-10-05 |
| c3.k8s.ooo | Test p7 PI | - | UNUSED | 2021-10-05 |
| c4.k8s.ooo | Dev2 p7 HW | Fran/Jin-Guk | server52 server53 server54 | - |
| c5.k8s.ooo | Dev p6 VM Amal | Nico/Amal | 2a0a-e5c0-2-11-0-62ff-fe0b-1a46.k8s-1.place6.ungleich.ch | |
| p6.k8s.ooo | production | | server67 server69 server71 | 2021-10-05 |
| p10.k8s.ooo | production | | server63 server65 server83 | 2021-10-05 |
| | | | | |
h2. General architecture and components overview
* All k8s clusters are IPv6 only
* We use BGP peering to propagate podcidr and serviceCidr networks to our infrastructure
* The main public testing repository is "ungleich-k8s":https://code.ungleich.ch/ungleich-public/ungleich-k8s
** Private configurations are found in the **k8s-config** repository
h3. Cluster types
| **Type/Feature** | **Development** | **Production** |
| Min No. nodes | 3 (1 master, 3 worker) | 5 (3 master, 3 worker) |
| Recommended minimum | 4 (dedicated master, 3 worker) | 8 (3 master, 5 worker) |
| Separation of control plane | optional | recommended |
| Persistent storage | required | required |
| Number of storage monitors | 3 | 5 |
h2. Operations
h3. Get the argocd credentials
<pre>
kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d; echo ""
</pre>
h3. Installing a new k8s cluster
* Decide on the cluster name (usually *cX.k8s.ooo*), X counting upwards
** Using pXX.k8s.ooo for production clusters of placeXX
* Use cdist to configure the nodes with requirements like crio
* Decide between single or multi node control plane setups (see below)
** Single control plane suitable for development clusters
Typical init procedure:
* Single control plane: @kubeadm init --config bootstrap/XXX/kubeadm.yaml@
* Multi control plane (HA): @kubeadm init --config bootstrap/XXX/kubeadm.yaml --upload-certs@
h3. Deleting a pod that is hanging in terminating state
<pre>
kubectl delete pod <PODNAME> --grace-period=0 --force --namespace <NAMESPACE>
</pre>
(from https://stackoverflow.com/questions/35453792/pods-stuck-in-terminating-status)
h3. Listing nodes of a cluster
<pre>
[15:05] bridge:~% kubectl get nodes
NAME STATUS ROLES AGE VERSION
server22 Ready <none> 52d v1.22.0
server23 Ready <none> 52d v1.22.2
server24 Ready <none> 52d v1.22.0
server25 Ready <none> 52d v1.22.0
server26 Ready <none> 52d v1.22.0
server27 Ready <none> 52d v1.22.0
server63 Ready control-plane,master 52d v1.22.0
server64 Ready <none> 52d v1.22.0
server65 Ready control-plane,master 52d v1.22.0
server66 Ready <none> 52d v1.22.0
server83 Ready control-plane,master 52d v1.22.0
server84 Ready <none> 52d v1.22.0
server85 Ready <none> 52d v1.22.0
server86 Ready <none> 52d v1.22.0
</pre>
h3. Removing / draining a node
Usually @kubectl drain server@ should do the job, but sometimes we need to be more aggressive:
<pre>
kubectl drain --delete-emptydir-data --ignore-daemonsets server23
</pre>
h3. Readding a node after draining
<pre>
kubectl uncordon serverXX
</pre>
h2. Infrastructure versions
h3. ungleich kubernetes infrastructure v3
* rook is now installed via helm via argocd instead of directly via manifests
h3. ungleich kubernetes infrastructure v2
* Replaced fluxv2 from ungleich k8s v1 with argocd
** argocd can apply helm templates directly without needing to go through Chart releases
* We are also using argoflow for build flows
* Planned to add "kaniko":https://github.com/GoogleContainerTools/kaniko for image building
h3. ungleich kubernetes infrastructure v1
We are using the following components:
* "Calico as a CNI":https://www.projectcalico.org/ with BGP, IPv6 only, no encapsulation
** Needed for basic networking
* "kubernetes-secret-generator":https://github.com/mittwald/kubernetes-secret-generator for creating secrets
** Needed so that secrets are not stored in the git repository, but only in the cluster
* "ungleich-certbot":https://hub.docker.com/repository/docker/ungleich/ungleich-certbot
** Needed to get letsencrypt certificates for services
* "rook with ceph rbd + cephfs":https://rook.io/ for storage
** rbd for almost everything, *ReadWriteOnce*
** cephfs for smaller things, multi access *ReadWriteMany*
** Needed for providing persistent storage
* "flux v2":https://fluxcd.io/
** Needed to manage resources automatically